JP2634739B2 - Liquid metal cooled reactor plant - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a heat-generating fissile fuel core, such as the type disclosed in U.S. Pat. No. 4,508,677, issued Apr. 2, 1985, to a liquid metal. The present invention relates to an improvement of a liquid metal-cooled nuclear reactor plant fully immersed in a pool.

[0002]

BACKGROUND OF THE INVENTION During operation of a liquid sodium or sodium-potassium metal-cooled power reactor, it is necessary to stop the fission reaction of the fuel in order to deal with emergencies or to perform regular maintenance services. Sometimes. Reactor shutdown is achieved by inserting a neutron absorption control rod into the core of the fissionable fuel to deprive the fuel of the neutrons necessary for fission to occur. However, a large amount of heat continues to be generated by the collapse of the fuel in the stopped reactor, which must be dissipated from the reactor unit.

[0003] The heat capacity of the liquid metal coolant and adjacent structures helps dissipate residual heat. However, reactor structural materials may not be able to safely withstand prolonged high temperatures. For example, the concrete on the walls of a typical containment silo can spread and crack when exposed to high temperatures.
Therefore, auxiliary cooling systems are commonly used to safely remove heat from the reactor structure during shutdown.

[0004] Conventional nuclear reactors have used various complex energy driven cooling systems to dissipate heat from the nuclear reactor. In many situations where an outage occurs, the energy source of the cooling system causes the cooling system itself to fail. For example, pumps and ventilation systems for providing core cooling may fail. Further, there is a foreseeable scenario in which the operator cannot take appropriate measures if operator intervention is required. The most reliable and desirable cooling system is a completely passive system capable of continuously removing residual heat generated after shutdown, regardless of the state.

US Pat. No. 4,508,677 uses sodium or sodium-potassium as a coolant.
Liquid metal cooled nuclear reactors, such as the modular type disclosed in U.S. Pat. Water cooled reactors operate at or near the boiling point of water. If the temperature rises significantly, steam will evolve and the pressure will increase. In contrast, the boiling point of sodium or sodium-potassium is very high,
At 1800 degrees Fahrenheit in barometric pressure. Normal operating temperatures for nuclear reactors are in the range of about 900 degrees Fahrenheit. The high boiling point of the liquid metal eliminates the pressure problems associated with water cooled reactors and the steam they generate. Due to the heat capacity of the liquid metal,
The sodium or sodium-potassium can be heated to several hundred degrees Fahrenheit without risk of material failure in the reactor.

[0006] The reactor vessel for a pool-type liquid metal cooled reactor is essentially a cylindrical tank with an open top and no holes that impede the integrity of the vessel wall. Sealing of the side and bottom walls is essential to prevent liquid metal from leaking from the primary container. The surface of the container must be accessible for the stringent inspection required for safety considerations.

[0007] In a typical sodium cooled reactor, two levels of heat transfer sodium loops or cooling circuits are used. Typically, a single primary loop and two or more secondary loops are used. The primary heat transfer loop contains highly radioactive sodium heated by the fuel rods. The primary loop passes through a heat exchanger and exchanges heat with one of the non-radioactive secondary sodium loops. In general,
Sodium cooled reactors are designed to include redundant secondary heat transfer loops in the event of a single loop failure.

When the reactor is shut down by fully inserting control rods, residual heat is generated and dissipated according to the heat capacity of the plant. If the reactor were at full power for a long time, during the first hour following shutdown,
An average of about 2% of the total output continues to be generated. The residual heat generated continues to decay over time.

Exaggerated traditional safety practices to handle the assumed worst-case scenario accident conditions deal with the event that both the reactor vessel and containment or protection vessel fail simultaneously. Questions have arisen about the means for doing so. When such an event occurs, the coolant level (liquid level) in the reactor vessel is significantly reduced due to the loss of liquid coolant due to the resulting leakage.
Reduced reactor coolant levels can significantly impede or interrupt normal coolant circulation through coolant loops or circuits that transfer heat away from the fuel core during routine operation. This hindrance or termination due to reduced coolant levels also applies to designed passive cooling systems that use unique processes including natural convection, conduction, radiation, and convection of fluids as a means of removing heat by heat transfer. Other such unlikely extremes that can affect coolant levels include hypothetical core disassembly accidents and maintenance accidents that result in damage within the reactor closure head. The core disassembly damages the fuel core,
Coolant spills occur, such as sodium rising up into the head access area of the reactor structure.

[0010] The present invention relates to a method for stopping decay heat from a liquid metal cooled reactor such as the unit disclosed and claimed in US Patent No. 4,678,626 issued December 2, 1985. Safety system improvements to deal with it are included. The above-mentioned US Pat.
The disclosures of 8,677 and 4,678,626 are incorporated herein by reference.

[0011]

OBJECTS OF THE INVENTION The main object of the present invention is to collapse the
Passive cooling for liquid metal-cooled reactors to remove sensible heat
It is to improve the safety system. Another eye of the present invention
Nuclei fully submerged in a pool of liquid metal coolant
Passive cooling of a liquid metal-cooled reactor containing a fissionable fuel core
Measures to enhance protection by indirect cooling safety measures
Is to provide. Another object of the present invention is to provide reactor cooling.
Auxiliary cooling to remove heat from reduced levels of waste material
Of a passive cooling safety system in a liquid metal-cooled nuclear reactor
To provide additional safeguards. The present invention
Yet another purpose is to be completely passive,
Operates due to the inherent phenomena of convection, conduction, convection and thermal radiation
The operational safety of an evolving liquid metal-cooled reactor heat removal system
To provide a means to do so. Still another of the present invention
Purpose Enables Destructive Effects Of Leaked Liquid Metal Coolant
Protect and leak liquid metal coolant from plant components
Shut down or shut down in a liquid metal cooled reactor
Passive to remove decay sensible heat generated during accident suspension
It is to provide a safety system.

[0012]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention
(A) a fixed first, including an open-top silo;
Structure, (B) seismic isolation
the second structure supported by the means
Liquid-metal cold with a core of heat-generating fissile fuel
The reactor vessel containing the reject material pool and the reactor vessel
Case that effectively surrounds the reactor vessel at a distance to the reactor
Gas between the reactor vessel and containment vessel.
A closed space is formed for holding
The reactor vessel and containment vessel are placed in the silo of the first structure.
Extending concentrically downwards at a distance, the silo effectively reduces
A surrounding second structure, and (C) a first structure.
Disposed between the upper annular lip of the structure and the second structure.
Liquid containing a combination of curved annular flexible sealing members
To provide a group-cooled nuclear reactor plant. Earthquake isolation means
This device prevents the transmission of earthquakes and is supported by the first structure.
Of seismic isolation buffers
The second structure is placed on the first structure, and the second structure is the first structure.
Keep a short distance from your body. Of the first structure
Arranged in the space between the upper annular lip and the second structure
The annular flexible sealing member is sealed when exposed to heat.
Hollow flexible tube ring containing gas to inflate the tool
It consists of. Alternatively, an annular flexible sealing member can
When the silo liner tank overheats,
First structure due to the inherent expansion of the silo liner tank
A member for closing tightly between the body and the second structure, for example
Consists of a continuous, compressible mass of flexible material
It is.

[0013]

DETAILED DESCRIPTION As shown in FIG. 1, current liquid metal cooled reactor designs use a double-walled reactor vessel which is effectively enclosed in an underground silo structure. By placing the reactor vessel containing liquid metal in the ground, it is likely that the double wall of the concentrically located reactor vessel (pressure vessel) and the surrounding containment vessel will burst. It is easier to keep the liquid metal coolant leaking out in case of no accidents.

Further, recent designs proposed for such liquid metal cooled reactor plants include passive cooling systems. A typical system includes one or more pairs of heat exchange fluid circuits provided in various configurations. These heat exchange fluid circuits operate by the natural phenomena of thermally induced fluid convection, conduction, radiation and convection, removing excessive heat from certain components of the reactor plant. For example,
The first fluid flow conduit of the heat exchange circuit, which operates by natural convection, draws in the cold atmosphere and descends towards the superheated part of the plant, and the second fluid flow conduit of the heat exchange circuit is continuously, and consequently, heated. The air is passed upward and returned to the atmosphere.

[0015] Such passive cooling systems operate by their own natural phenomena, with the operator or instrument for initiating a manual or mechanical action for cooling, or power for achieving an auxiliary cooling function. And requires no mechanical or chemical means.

A liquid metal-cooled nuclear reactor plant 10 provided with such a passive auxiliary cooling safety system is partially shown in FIG. The reactor plant 10 includes a reactor vessel 12,
The reactor vessel 12 is constituted by a cylindrical tank whose upper part is open and whose longitudinal axis is arranged to extend substantially vertically upward. This tank isolates the contents of the reactor vessel,
It also has a removable cover 14 for access. The reactor vessel 12 includes a core 16 of fissile fuel material that generates heat. The core 16 has a large number of control rods 1 containing a neutron absorbing substance.
8 are provided. The control rods 18 can reciprocate into and out of the core 16 to adjust the fission rate or stop the heat production reaction.

The reactor vessel 12 contains a pool 20 of liquid metal coolant. The liquid metal coolant covers the heat generating core 16 and circulates through one or more coolant loops or circuits. Thereby, heat is transmitted from the fuel core and sent to a certain position. At this location, heat is used and consumed to generate steam or perform other tasks. Common liquid metal coolants are sodium or potassium metals, which are liquid at appropriate reactor operating temperatures and exhibit high specific heat temperatures.

A storage container 22 comprising a cylindrical tank which is open at the top and arranged so that the vertical axis is substantially vertical.
Are concentrically arranged so as to surround the cylindrical reactor vessel 12 at intervals. This provides a closed space between the two juxtaposed walls of the reactor vessel and containment vessel. The space between the reactor vessel and the containment vessel is sealed,
Gas is in. This gas is an inert gas such as, for example, nitrogen or argon and does not react with the liquid metal coolant. This gas surrounding the reactor vessel 12 containing the liquid metal acts as a protective barrier in the event that coolant leaks from the reactor vessel into this space, and the reactor vessel 1
2 and its radioactive contents are isolated from the surrounding atmosphere.
The particular gas mixture that fills the intermediate space is a highly reactive liquid metal coolant 14 such as sodium or potassium.
Must not react with

A stationary structure (ie, a stationary structure)
25 is almost buried underground, open silo 2
4 At least the majority of the vertical cylindrical enclosure structure of silo 24 is below ground level. The fixed silos 24 buried firmly underground provide a solid foundation for the reactor plant 10 and the silo cavities 26. Silo 24 is made at least in large part of concrete and / or metal. Silo cavity 26 is generally
Consists of a buried cylindrical tank with an open top and a vertical axis that is almost vertical.

In order to cope with earthquakes, modern liquid metal-cooled reactors have shifted more important components and structures from ground movement.
It has been designed to provide isolation (ie, seismic isolation) .
For example, in one design, the reactor vessel 12 and its protection
Superstructure over which the composite of containment vessel 22 for
extending downward from 28
Connected to the substructure. This upper structure 28
Contains other plant components that are susceptible to earthquakes
You. Upper structure 2 holding reactor vessel and containment vessel
8 constitutes the stationary structure 25 via the seismic isolation means.
Mounted on the upper structural part of the silo 24
You. Specifically, holding the reactor vessel and containment vessel
The upper structure 28 includes a spring, a rubber pad and a hydraulic shock absorber.
Is placed on the shock absorber 30 such as
More supported. These springs, rubber pads and hydraulic
A shock absorber such as a shock absorber constitutes the stationary structure 25 (underground)
Silo 24 or silo liner tank)
32 to the upper annular surface or flange extending around
Is determined.

The silo 24 for a liquid metal cooled reactor is typically provided with a silo liner tank 32 made of a suitable and durable metal, such as steel, to withstand the effects of contact with the liquid metal coolant. It is preferred to protect against such leaking liquid metal coolant erosion. Metal sa
The use of an iro liner tank 32 is particularly important in the case of concrete silos 24 which are susceptible to erosion such as liquid sodium. Above silo liner tank 32
Preferably , a flange 34 is provided at the edge of the part . The flange 34 extends outward beyond the upper surface of the concrete silo 24 to spread its protective action to all exposed surfaces.

Further, it is usually preferred to provide a thermal insulator 36 between the silo liner tank 32 and the concrete silo 24. The heat insulator 36 to maintain the integrity of the silo by shielding from high temperatures, such as to damage the silo. Separating these juxtaposed components from each other, i.e. separating the double wall of the reactor vessel and containment vessel from the silo liner tank with outer insulation, and the silo Liner tank
By separating from the silo , a void space between the above components, for example, the wall of the containment vessel 22 and the silo
A space 38 is formed between the space 38 and the liner tank 32. These void spaces sequentially enhance the thermal insulation protection of all components outside the reactor vessel.

The space 38, or the adjacent space between components such as vessels, can be used to provide additional cooling to remove excess heat generated by decay heat or abnormalities during shutdown. For example, an auxiliary passive cooling system for removing heat from around the reactor vessel provides one or more heat exchange fluid circuits. In this heat exchange fluid circuit, an external air flow descending from the atmosphere in such a space occurs,
The rising temperature and decreasing density of the air due to the absorption of heat causes an upward flow that rises in such spaces. Thereby, the heat transfer air is discharged and returns to the atmosphere.

A typical passive auxiliary cooling system for removing heat generated by fuel collapse during reactor shutdown or excessive heat generated during abnormal periods as described above includes heat transfer forming an auxiliary heat exchange circuit. A number of sealed fluid flow conduit pairs called tubes are included. As shown in FIG. 1, a first fluid flow heat exchange conduit 40 is provided to draw in the cold atmosphere and lower it to a superheated area in space 38. This transfers heat to the air. The air stream thus heated is driven by its low density and flows upward through the second fluid flow heat exchange conduit 44 and exits to the atmosphere.
Thermal energy transferred to the lower part of the reactor plant is dissipated into the atmosphere. Such auxiliary passive cooling systems, which are closed or sealed to locations or components inside the reactor plant, remove heat from them by indirect means. In this way, the auxiliary passive cooling system does not release radioactive contaminants with heat to the outside atmosphere.

An extreme and unlikely hypothetical event that must be considered for safety is that both reactor vessel 12 and containment vessel 22 rupture, and these vessels and silo 24
If there is any barrier between them, this barrier will also burst. Due to such an event, the liquid metal coolant 2
0 with leaking into silo 24 within the reactor vessel, fuel
It can happen that the level of coolant remaining in the reactor vessel (liquid level) in order to carry heat away from the core of the fuel is reduced in an instant. High-temperature liquid metal coolant, such as sodium, leaking into silos made of concrete containing hydraulic cement, causing chemical reactions with heat,
Sodium fires and elevated concrete temperatures can occur. This reduces the structural integrity of the load-bearing silo 24 walls, so that groundwater enters the underground reactor cavity and reacts explosively with the leaked hot sodium. As a result of such events, not only intense radiation emissions, but also weakening of the reactor foundation or support system may occur, with consequent unknown catastrophic consequences.

If liquid metal coolant leaks into the space between vessel components due to the rupture of the vessel, the sodium level in the reactor vessel will drop, thus disrupting the normal cooling heat exchange circuit and fluid flow therethrough. Will be As a result of this significant loss of heat removal function and system, the fuel sodium decay heats the liquid sodium coolant in the core area, causing the sodium coolant to start boiling within a few hours, causing fuel rod damage and cooling the fuel. Release into the material. Theoretically, radiation emission can occur through a ventilation gap 52 that provides direct communication between the reactor cavity and the outside atmosphere. Heat is continuously removed from the sodium contained in the cavity 38 through the auxiliary heat exchange circuit, thereby preventing sodium boiling in this region.

According to one aspect of the invention, silo 24 or
Is a stationary structure 25 such as a silo liner tank 32.
Upper structure 2 supported by upper part and seismic isolation means
At least one annular seal member 48 is disposed between the first and second seal members 8. The sealing member 48 is cut off while the reactor cavity from the outside atmosphere, the stationary structure 25 buried
A means is provided for absorbing different magnitudes of seismically induced movement between the superstructure 28 supported by the seismic isolation means .

The seal member (s) 48 typically have a support extending upwardly to the lower surface of the upper structure 28.
It is fixed on the upper surface of the iro 24 or the silo liner tank 32. Stationary structures 25 during severe earthquake events
Preferably, the sealing member 48 is constructed and secured to accommodate horizontal movements of up to about 20 inches and vertical differential movements of up to about 0.5 inches between the upper and lower structures 28. In operation of a typical power-generating liquid metal-cooled reactor, seal member 48 may comprise an annular unit having a diameter of, for example, about 30 feet or more. Also, the seal member (s) 48 should be made of a material that will withstand radiation over an extended period of time.

[0029] The seal member 48 of the present invention is constructed from a variety of suitable materials. These include polysiloxanes (Bisco Products, I
nc. Or a continuous ring of hollow gas-filled tubes composed of an elastic polymer or elastomeric material. In the latter case, the sealed gas expands due to the heat resulting from the abnormality of the nuclear reactor, and the tubular sealing member expands, thereby improving the sealing function. The sealing member 48 can be used alone or in FIG.
Can be used in multiple, for example, two or more, parallel or concentric units. Further, in addition to a substantially circular or oblong tubular seal as shown in FIG. 2, a compressible mass of a flexible material having a square or rectangular cross section as shown in FIG. 1 can be used.

The sealing member 48 should be held at a suitable location around the top of the stationary structure 25 , for example, at the top of the silo wall, or an extension thereof, or at the top edge or top flange of the silo liner tank 32. Suitable fixing means comprise a bracket 50, for example an L-shaped or square iron unit, a grooved surface, an adhesive or the like. The sealing member 48 is located on the surface of the upper
So that they do not physically contact the surface ,
An annular gap 52 between the upper structure 28 and about 1
Preferably, a space of up to inches is provided and maintained during normal reactor operating conditions. Such a gap 5
2 prevents the seal member from directly contacting the lower side of the upper structure 28. This ensures unrestricted relative movement between the seal member 48 and the superstructure 28 during a seismic event, and during the initial period of the assumed double vessel 12 and 22 leak event, Significant pressure build-up in the reactor cavity is avoided because a leakage path for combustion products is maintained.

A unique feature of the present invention is that the sealing member 48 fits tightly when the steel silo liner tank 32 is heated to about 700 degrees Fahrenheit by exposure to hot sodium or sodium fire following a double vessel leak. Is to close. As the silo liner tank 32 heats up, it expands upwards to about two inches. Thus, after the accident as described above, the stationary structure 25 and the upper structure thereon
Gap of 1 inch or less that constitutes a vent with body 28
The lid 52 is closed to form an airtight seal. Concrete silo 24 and steel silo / liner tank 32
Alternatively, the space between it and the thermal insulator 36 provided thereon serves as a steam vent path for venting steam (steam) from the concrete silos following a double vessel leak. But Silo Linata
The thermal insulation 36 of the link limits heating to an acceptable level such that the structural integrity of the concrete is not significantly reduced.

One variation of the present invention is shown in FIGS. This is fixed by being virtually buried in the ground
2 shows the deformation of a reactor silo cavity including a stationary structure .
In this variant, the silo 24 is made of structural steel. Structural steel has several advantages in this application. For example, steel
The iron silo 24 loses the passive air cooling system and the system valve 42
And 46 provide a rear heat removal system when closed. Because heat is more easily transmitted through the steel wall structure to the surrounding earth and groundwater provides for shutdown cooling following very unlikely hypothetical events as described above,
This is because it can be enhanced. In addition, this structural steel silo can be enhanced by providing a back ground water cooling system designed to mitigate the effects of double vessel cracking leading to interference with the auxiliary passive fluid heat exchange circuit as described above. it can.

As shown in FIGS. 6 and 7, a support including a cylindrical tank with an open top and a vertical axis is oriented vertically.
The iro (24) is made of steel. This vertical steel support
Iro is also effectively buried and fixed in the ground. By putting down a large portion of the steel tank from the ground surface, a constant
A mounting structure is obtained. Steel silo is outer steel container 54
And an inner steel container 56. Also, the silo spacing
Outer steel container 54 and inner steel container 56 placed side by side
In the space between and the high thermal conductivity granular filler material 56,
For example, iron granules are filled. Vertical steel beam 60
Preferably extend inward from the inner surface of the outer steel container 54, but preferably do not contact the outer surface of the inner steel container 56. Preferably, the radially arranged vertical steel beams are provided with a plurality of horizontal steel braces 62 or webs extending between the vertical steel beams 60 at several levels passing through the granular filled thermally conductive material 58.

The coarse-grained barrier layer 64 surrounds the outer steel vessel of the reactor silo structure to form a porous material surrounding body to prevent the inflow of fine soil and to reduce the inflow of groundwater in the compartment. It is preferable to be able to do so. This gravel barrier layer 64 around and below the reactor silo is highly permeable to water and steam flows.

A steam vent pipe 66 having several holes is provided. The vapor escape pipe 66 exits the atmosphere from near the bottom of the reactor silo, passing upward through a water-permeable gravel barrier layer that supports and surrounds the silo structure, and rises above the surface. Therefore, if the silo structure overheats due to a hypothetical accident such as a crack in a double vessel, adjacent groundwater in the surrounding permeable gravel evaporates to steam, which is passed through a vent pipe. Transported to the atmosphere above the earth's surface. This system is particularly useful as a heat exchanger in removing heat from silo structures.

If the location of the reactor is relatively dry or a rock formation, the water for this unique ground heat exchanger can be supplied from any source to an area adjacent to the bottom of the silo structure. Through several descending pipes 68 gravity can feed permeable gravel around the silo structure.

This variant of the invention overcomes the problem that liquid metal coolants, such as sodium, are not compatible with concrete containing bud cement. When the unlikely event that sodium leaks into the silo structure occurs, no danger arises if the sodium reaches the structure formed of concrete. In addition, the steel silo structure has good heat transfer properties and can be effectively dissipated into groundwater surrounding the decay heat and cooled by evaporation.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view of a liquid metal-cooled nuclear reactor plant of the present invention.

FIG. 2 is an enlarged view showing a modification of some details of the structure of the embodiment of FIG. 1;

FIG. 3 is an enlarged view showing another modification of some details of the structure of the embodiment of FIG. 1;

FIG. 4 is an enlarged view showing another modification of some details of the structure of the embodiment of FIG. 1;

FIG. 5 is an enlarged view showing yet another modification of a part of the structure of the embodiment of FIG. 1;

FIG. 6 is a schematic sectional view showing a modification of the liquid metal cooled nuclear reactor plant of the present invention.

FIG. 7 is an enlarged view showing a modification of a part of the structure of the embodiment of FIG. 6;

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 10 Liquid metal-cooled nuclear reactor plant 12 Reactor vessel 16 core 20 Liquid metal coolant 22 Containment vessel 24 Silo 25 Stationary structure 28 Upper structure 30 Buffer 32 Silo / liner tank 36 Thermal insulator 48 Seal member 54 Outside of silo Steel container 56 Inside steel container of silo 58 Granular filled thermal conductive material 60 Beam

 ──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-59-63592 (JP, A) JP-A-3-18793 (JP, A) JP-A-59-150382 (JP, A)

Claims (4)

(57) [Claims] 1. A liquid metal-cooled nuclear reactor plant, comprising: a first stationary structure, including a silo with an open top , a second structure supported by seismic isolation means,
Includes a reactor vessel containing a pool of liquid metal coolant with a core of heat-generating fissile fuel immersed therein, and a containment vessel substantially spaced from and surrounding the reactor vessel. A sealed space for holding gas is formed between the reactor vessel and the containment vessel, and the reactor vessel and the containment vessel are concentrically spaced apart in the silo of the first structure. extends downward, the second structure is surrounded virtually by silos, and a first upper annular rim and a flexible seal member arranged annularly between the second structure of the structure A liquid metal cooled atom comprising a combination of annular flexible seal members comprising a hollow flexible tube ring containing a gas that expands the seal when subjected to heat. Furnace plant. 2. A In liquid metal cooled nuclear reactor plant, the shaft is arranged vertically in the cylindrical upper part is open support
A stationary first structure, including an iro , mounted on a seismic isolator supported by the first structure
The first structure being a short distance from the first structure
A second structure, at a cylindrical reactor vessel containing a pool of the heat generating fissionable liquid metal coolant core soaked in fuel, apart concentrically with respect to the reactor vessel A cylindrical containment vessel substantially surrounding the reactor vessel,
A sealed space is formed between the reactor vessel and the containment to hold the protective gas, and the cylindrical reactor vessel and the containment are concentrically lowered downward in a cylindrical silo . to extend, a second structure is surrounded virtually by silos, and the first structure above the annular rim and flexible in arranged annular space between the second structure of the A liquid metal comprising a combination of annular flexible seal members comprising a hollow flexible tube ring containing a gas that expands the seal when subjected to heat. Cooling reactor plant. 3. A stationary first structure in a liquid metal-cooled nuclear reactor plant , wherein the stationary structure comprises a concrete cylindrical silo having a vertical axis and an open top.
Body, over multiple seismic isolation buffers supported by the first structure
At a short distance from the first structure
A second reactor structure comprising a cylindrical reactor vessel containing a pool of liquid metal coolant having a core of heat-generating fissile fuel immersed therein, and concentric with said reactor vessel. A sealed containment space for holding protective gas between the reactor vessel and the containment vessel, comprising a cylindrical containment vessel substantially surrounding the reactor vessel at a distance; Furnace vessel and containment vessel are concrete cylindrical
Extends downward concentrically spaced within the silo, the second structure is surrounded virtually by silos <br/>, and a first upper annular rim and a second structure of the structure and at least one flexible sealing member annular disposed within the space between the body, the first structure by the inherent expansion of the silo liner tank overheated when silo liner tank is overheated by accident A liquid metal-cooled nuclear reactor plant comprising a combination of at least one annular flexible seal member that provides a tight closure between the body and the second structure . 4. The liquid metal-cooled nuclear reactor plant according to claim 3, wherein the annular flexible sealing member comprises a continuous compressible mass of flexible material.